New to hosting a server Help needed

I have recently purchased a Gmod server from nfo and I dont know how to change the gamemode, add maps, Add svn links, Add addons. I would like help with this it is probably very simple I am new to this so please dont make fun of me. Thank You
Can I get any help from someone?

I’ll gladly help you. First off, Who is your host? Mine is NFO - Or Nuclear Fallout.